This standard establishes requirements for biometric recognition systems that could become subject to morphing attacks. The standard establishes: • Taxonomy of biometric sample modifications and manipulation with a specific focus on manipulations that constitute a multiple identity attack. This can be for instance an enrolment attack with face image morphing. • Requirements for testing databases that contain bona fide (i.e. pristine) and morphed images. • Methodology to measure the attack potential of a morphing method constituted with a dataset of morphed images. Based on the methodology the user of the standard can simulate a real use case (for example issuance of documents or border control) with a variable number of attempts (i.e., multiple probe images acquired at the gate) and multiple biometric recognition systems (i.e., to simulate ABC gates from different vendors), in order to determine the attack potential against biometric recognition systems. The standard includes informative content on how morphing algorithms can be used for system evaluation. The standard is intended to support evaluations of biometric recognition systems with respect to multiple identity attack.